Population Pyramids & the DTM🌱 Env. Science course
Scored investigationUnit 3 · Populations Data analysis

Find the stage where population growth peaks, and explain why it peaks there

Three steps, the way the exam actually works: work through the lab, write down your own observations, then answer a 7-point free response. What you recorded goes to the grader with your writing, so a conclusion that does not follow from your own evidence will cost you the point — exactly as it would with a real reader.

1

Predict before you look

Before you start
  • Natural increase is births minus deaths. If a society has both a very high birth rate and a very high death rate, is its population growing quickly, slowly, or hardly at all?
  • Doubling time is 70 divided by the percent growth rate. What happens to that number as the growth rate approaches zero — and what does it mean if the growth rate is negative?

Nothing to submit here — these are to think through, so the prediction below is an informed one rather than a guess.

Commit to an answer now. It is not graded and being wrong costs nothing — the point is to have something specific to reconcile against once you have the data.

Answer every prediction to unlock the lab. A sentence is enough.

2

Run the investigation

Predictions first

The procedure and the simulation unlock once you have committed above. Observing before predicting is how a wrong intuition survives a lab intact.

3

Record what you found

This is your reading of the source, not ours. The grader sees them, so your conclusions have to follow from what you actually recorded.

Data table for Find the stage where population growth peaks, and explain why it peaks there
Stage 1 CBR
per 1,000
Stage 1 CDR
per 1,000
Stage 1 NIR
%
Stage 2 CBR
per 1,000
Stage 2 CDR
per 1,000
Stage 2 NIR
%
Stage 2 doubling time
yr
Stage 3 NIR
%
Stage 4 NIR
%
Stage 4 doubling time
yr
Stage 5 NIR
%
What the lab prints for Stage 5 doubling time
0/12 entries recorded11 of 12 cells are auto-checked; the rest depend on choices the procedure left to you
4

Answer the free response

Prompt
7 pts

You have recorded crude birth rate, crude death rate, natural increase and doubling time across all five stages of the demographic transition model. (a) Identify the stage with the fastest population growth and cite the NIR and doubling time you recorded there. (b) Using your CBR and CDR columns, explain what causes the growth spike — name the rate that moves first and give two concrete reasons it moves. (c) Compare Stage 1 and Stage 4. Both have low natural increase. Explain why they are nevertheless completely different demographic situations, using your recorded rates. (d) Explain what the lab prints for the Stage 5 doubling time, why a number cannot be given there, and name one consequence a country in that position faces.

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